The Mighty, Ever-Sucking Maw of the Mississippi River

More than 50 cities draw their water from the mighty Mississippi—which, when combined with its conjoined twin the Missouri River, is the fourth-longest river in the world.

But where’s all that agua originating? Horace Mitchell at NASA’s Scientific Visualization Studio has the answer with this wonderful animation of the streams, rivers, and rivulets of spilled Southpaw Light (not pictured) that make up the vast Mississippi Watershed.

The Mississippi Watershed is the largest drainage basin in North America at 3.2 million square kilometers in area. The USGS has created a database of this area which indicates the direction of waterflow at each point. By assembling these directions into streamflows, it is possible to trace the path of water from every point of the area to the mouth of the Mississippi in the Gulf of Mexico. This animation starts with the points furthest from the Gulf and reveals the streams and rivers as a steady progression towards the mouth of the Mississippi until all the major rivers are revealed. The speed of the reveal of the rivers is not dependent on the actual speed of the water flow. The reveal proceeds at a constant velocity along each river path, timed so that all reveals reach the mouth of the Mississippi at the same time.

At the Mississippi’s origins in Lake Itasca, Minnesota, the average rate of flow is 6 cubic feet per second, according to the National Park Service. By the time all the water has compiled and is shooting out of the river’s mouth in New Orleans, the average flow is 600,000 cubic feet per second—which the service says is the “equivalent of 166 semi-trailers of water flow past Algiers Point each second.”